The Iris Festival is one of five seasonal events adopted from China. The fifth day of the fifth month was believed to be the occasion of evil spirits, bad luck and poisonous insects. As protection from these calamities, iris leaves were strewn on rooftops and attached to the eaves of houses. In ancient times, celebrations included martial displays performed before the emperor. Perhaps because of this, the day came to be associated with boys. During the Edo period (1600-1868), households with male children displayed flying banners (nobori) and helmets, and boys spent the day engaged in mock battles using wooden swords. Their costumes for this day, and other special events, often consisted of kimono patterned with symbols of masculine strength and determination, such as carp struggling against a river current.